Devices, systems, facilities and processes for multistage direct contact cooler design

ABSTRACT

A multistage direct contact cooler is configured to cool process gases for downstream process requirements. The multistage direct contact cooler includes a high temperature stage and a low temperature stage. Cooling duties for the high temperature stage of the direct contact cooler are achieved by air cooling. Cooling duties for the low temperature stage of the direct contact cooler are achieved by evaporative cooling with an option to include additional air cooling to reduce evaporative losses.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority to U.S.Provisional Application No. 63/303,687 filed Jan. 27, 2022, the entiretyof which is incorporated herein by reference.

BACKGROUND

Direct contact cooling is used in industrial processes to cool hot gasstreams for use in downstream processes, for example, cooling of fluegases for post-combustion carbon capture. The direct contact between thehot gas and the cooling media, typically water, leads to efficient heattransfer due to high amounts of heat transfer area and to the removal ofan intermediate heat transfer media (i.e. the materials typically usedto separate process streams).

External cooling duties for the direct contact cooling process are oftenprovided by the use of evaporative cooling, especially when the hotgases are to be cooled temperatures near local ambient dry bulbtemperatures. Evaporative and blowdown losses from evaporative coolingprocesses can be significant and place a strain on local waterresources.

Direct contact cooling processes can minimize unnecessary consumption ofwater by evaporative cooling processes by more efficiently allocatingcooling duties between air cooled processes and evaporative cooledprocesses.

SUMMARY

A multistage direct contact cooling process may include a multistagedirect contact consist of a high temperature stage and a low temperaturestage.

In a first aspect of the present disclosure, which may be combined withany other aspect listed herein unless specified otherwise, the hotprocess gas enters the high temperature stage of the direct contactcooler where it is cooled by contact with water. The water beingcontacted in the high temperature stage of the direct contact cooler iscooled using an air cooling device such as air cooled heat exchangers,chiller packages, or air-to-gas exchangers. The high temperature stageis designed such that cooling duty thereof is maximized and can becooled in a practical manner via the use of air-cooled heat exchangersor other cooling devices. In practice, this means the cooling watersupply temperature of the high temperature stage is above a local designdry bulb temperature plus approach temperature limitations of air-cooledheat exchangers. The approach temperature of the cooling water supplyand the cooled saturated process gases leaving the high temperaturestage should be minimized to ensure that the amount of cooling dutyperformed by the air-cooled heat exchangers is maximized. This resultsin a net reduction in the amount of cooling demand on the lowtemperature stage, and therefore reduces water losses in the evaporativecooling process.

In a second aspect of the present disclosure, which may be combined withany other aspect listed herein unless specified otherwise, the cooledsaturated process gas enters the low temperature stage of the directcontact cooler where it is further cooled by contact with water via anevaporative cooling device. The water being contacted in the lowtemperature stage of the direct contact cooler is cooled using anevaporative cooling process. The evaporative cooling process allows thecooling water to be cooled near the ambient wet bulb temperature. Thelow temperature stage is designed to perform the remaining cooling dutyrequired to cool the process gases to the temperature required in thedownstream process.

In a third aspect of the present disclosure, which may be combined withany other aspect listed herein unless specified otherwise, an additionalair-cooled process can be incorporated upstream of the evaporativecooling process. The addition of the air-cooled process upstream of theevaporative cooling process further reduces the cooling demand on theevaporative cooling process, and therefore reduces water loss due toevaporation and blowdown. In this arrangement, the evaporative coolingprocess operates as a trim cooler, performing the remaining requiredcooling duty that the air-cooled process was not able to perform. Thisarrangement takes advantage of variations in ambient conditions, whichallows the air-cooled process to perform higher relative amounts of therequired duty when ambient dry bulb temperatures are lower (i.e due toseasonal or daily variations).

Additional features and advantages of the disclosed devices, systems,and methods are described in and will be apparent from the followingDetailed Description and the Figures. The features and advantagesdescribed herein are not all-inclusive and in particular many additionalfeatures and advantages will be apparent to one of ordinary skill in theart in view of the figures and description. Also, any particularembodiment does not have to have all of the advantages listed herein.Moreover, it should be noted that the language used in the specificationhas been principally selected for readability and instructionalpurposes, and not to limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE FIGURES

Understanding that the figures depict only typical embodiments of theinvention and are not to be considered to be limiting the scope of thepresent disclosure, the present disclosure is described and explainedwith additional specificity and detail through the use of theaccompanying Figure.

FIG. 1 illustrates an exemplary schematic of a hot process gas streambeing cooled to downstream process required contact with cooling waterin a multistage direct contact cooler.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The detailed description is to be construed as exemplary only and doesnot describe every possible embodiment, as describing every possibleembodiment would be impractical, if not impossible. One of ordinaryskill in the art could implement numerous alternate embodiments, whichwould still fall within the scope of the claims. To the extent that anyterm is referred to in a manner consistent with a single meaning, thatis done for the sake of clarity and illustration only, and it is notintended that such claim term be limited to that single meaning.

FIG. 1 illustrates an exemplary schematic of a multistage direct contactcooler 100 being utilized at an industrial facility to cool hot processgases from upstream process(es) 101 to the required temperature for thedownstream process 104.

The hot process gases are sent to the high temperature stage 102 of thedirect contact cooler. In the high temperature stage 102, the hotprocess gases may be cooled via direct contact with cooling water. Theprocess gases are saturated with water and leave the high temperaturestage 102 as partially cooled saturated process gases.

The partially cooled saturated process gases then enter the lowtemperature stage 103 where the partially cooled saturated process maybe further cooled via direct contact with cooling water to thetemperature required by the downstream process 104. The process gasesare saturated with water and leave the low temperature stage 103 as coolsaturated process gases.

The cooling water circulated in the high temperature stage 102 is cooledby dry cooling 105. In some embodiments, the dry cooling 105 comprisesan air cooling device utilizing air cooling, such as an air-cooled heatexchangers. In alternative embodiments, a chiller package is used tocool the cooling water. In a further embodiment, ambient air could beused as the cooling medium with a gas-to-air heat exchanger. The coolingwater supply temperature for the high temperature stage 102 is designedsuch that it can be practically achieved via the use of air-cooled heatexchangers. For example, if the dry-bulb design temperature is 90° F.,the cooling water supply temperature for the high temperature stage maybe set at 110° F., allowing for a 20° F. approach temperature. Theapproach temperature can be reduced to as low as approximately 8° F.with more heat transfer area.

The cooling water circulation rate and the contact volume size of thehigh temperature stage 102 are designed to result in a close approachtemperature (<10° F.) between the cooling water supply temperature andthe partially cooled saturated process gases leaving the hightemperature stage 102. These design considerations maximize the coolingduty performed in the high temperature stage 102 which in tum reducesevaporative and blowdown losses associated with the evaporative coolingprocess 107 of the low temperature stage 103.

The cooling water circulated in the low temperature stage 103 may becooled by the evaporative cooling process 107 to a temperature ofapproximately 5-15° F. above wet-bulb temperature. The evaporativecooling process 107 utilizes an evaporative type cooler such as acooling tower or other suitable device. In processes where the desiredcooling water supply temperature is near or below the dry-bulbtemperature, evaporative cooling processes may be required. Dry coolingprocesses (i.e. air-cooled heat exchangers) are limited to by theapproach to the ambient dry-bulb temperature, whereas evaporativecooling processes are limited by the approach to the ambient wet-bulbtemperature which is lower than the ambient dry-bulb temperature.

The duty of the evaporative cooling process 107 is designed to achievethe required outlet temperature for the cool saturated process gases.Evaporative and blowdown losses are related to the duty and theallowable concentration of contaminants in the cooling water loop.Reductions in the required cooling duty of the evaporative coolingprocess 107 will result in reductions in evaporative and blowdownlosses.

Additional dry cooling 106 can be incorporated upstream of theevaporative cooling process 107 to reduce the duty of the evaporativecooling process 107. The dry cooling 106 performance will vary withambient dry-bulb temperatures, and can be designed to accommodate 100%of the low temperature stage 103 cooling duty at a specified dry-bulbtemperature. The evaporative cooling process 107 performs any residualcooling duty not performed in the dry cooling 106.

All percentages expressed herein are by weight of the total weight ofthe composition unless expressed otherwise. As used herein, “about,”“approximately” and “substantially” are understood to refer to numbersin a range of numerals, for example the range of −10% to +10% of thereferenced number, preferably −5% to +5% of the referenced number, morepreferably −1% to +1% of the referenced number, most preferably −0.1% to+0.1% of the referenced number. All numerical ranges herein should beunderstood to include all integers, whole or fractions, within therange. Moreover, these numerical ranges should be construed as providingsupport for a claim directed to any number or subset of numbers in thatrange. For example, a disclosure of from 1 to 10 should be construed assupporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to4.6, from 3.5 to 9.9, and so forth.

As used in this disclosure and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “an ingredient or“the ingredient” means “at least one ingredient” and includes two ormore ingredients.

The words “comprise,” “comprises” and “comprising” are to be interpretedinclusively rather than exclusively. Likewise, the terms “include,”“including” and “or” should all be construed to be inclusive, unlesssuch a construction is clearly prohibited from the context.Nevertheless, the compositions disclosed herein may lack any elementthat is not specifically disclosed herein. Thus, a disclosure of anembodiment using the term “comprising” includes a disclosure ofembodiments “consisting essentially of” and “consisting of” thecomponents identified. A composition “consisting essentially of”contains at least 75 wt. % of the referenced components, preferably atleast 85 wt. % of the referenced components, more preferably at least 95wt. % of the referenced components, most preferably at least 98 wt. % ofthe referenced components.

The terms “at least one of” and “and/or” used in the respective contextof “at least one of X or Y” and “X and/or Y” should be interpreted as“X,” or “Y,” or “X and Y.” For example, “at least one of honey orchicory root syrup” should be interpreted as “honey without chicory rootsyrup,” or “chicory root syrup without honey,” or “both honey andchicory root syrup.”

Where used herein, the terms “example” and “such as,” particularly whenfollowed by a listing of terms, are merely exemplary and illustrativeand should not be deemed to be exclusive or comprehensive. The manyfeatures and advantages of the present disclosure are apparent from thewritten description, and thus, the appended claims are intended to coverall such features and advantages of disclosure. Further, since numerousmodification and changes will readily occur to those skilled in the art,the present disclosure is not limited to the exact construction andoperation as illustrated and described. Therefore, the describedembodiments should be taken as illustrative and not restrictive, and thedisclosure should not be limited to the details given herein but shouldbe defined by the following claims and their full scope of equivalents,whether foreseeable or unforeseeable no or in the future.

The invention is claimed as follows:
 1. A process for cooling hotprocess gases, the process comprising: providing a multi-stage directcontact cooler configured to cool the hot process gases, the multi-stagedirect contact cooler comprising a high temperature stage and a lowtemperature stage; air cooling a first cooling water configured to becirculated in the high temperature stage; and evaporative cooling asecond cooling water configured to be circulated in the low temperaturestage.
 2. The process of claim 1, wherein the air cooling is provided byone of an air-cooled heat exchanger, a chiller package, and a gas-to-airheat exchanger.
 3. The process of claim 1, further comprising the stepof air cooling the second cooling water configured to be circulated inthe low temperature stage upstream.
 4. The process of claim 1, wherein adifference between a cooling water supply temperature of the firstcooling water entering the high temperature stage and a temperature ofpartially cooled saturated process gases exiting the high temperaturestage is less than about 10° F.
 5. A process for cooling hot processgases, the process comprising: providing a multi-stage direct contactcooler configured to cool the hot process gases, the multi-stage directcontact cooler comprising a high temperature stage and a low temperaturestage; cooling, via at least one air-cooled heat exchanger, a firstwater media configured to be circulated in the high temperature stage,the at least one heat exchanger configured to supply cooling duty to thehigh temperature stage; and cooling, via at least one evaporative typecooler, a second cooling water configured to be circulated in the lowtemperature stage, the at least one evaporative type cooler configuredto supply cooling duty to the low temperature stage.
 6. The process ofclaim 5, further comprising the step of cooling, via at least onefurther air-cooled heat exchanger, the second cooling media upstream ofthe at least one evaporative type cooler.
 7. The process of claim 5,wherein the at least one evaporative type cooler comprises a coolingtower.
 8. The process of claim 5, wherein a difference between a coolingwater supply temperature of the first cooling water entering the hightemperature stage and a temperature of partially cooled saturatedprocess gases exiting the high temperature stage is less than about 10°F.
 9. A process for cooling hot process gases, the process comprising:providing a multi-stage direct contact cooler configured to cool the hotprocess gases, the multi-stage direct contact cooler comprising a hightemperature stage and a low temperature stage; cooling, via a first aircooling device, a first cooling water configured to be circulated in thehigh temperature stage, the at least one heat exchanger configured tosupply cooling duty to the high temperature stage; cooling, via a secondair cooling device, a second cooling water configured to be circulatedin the low temperature stage, the at least one evaporative type coolerconfigured to supply at least a first portion of the cooling duty to thelow temperature stage; and cooling, via at least one evaporative typecooler, the second cooling water downstream of the at least oneair-cooled heat exchanger, wherein the at least one evaporative typecooler is configured to provide a second portion of the cooling duty tothe lower temperature stage.
 10. The process of claim 9, wherein each ofthe first and second air cooling devices comprises one of an air-cooledheat exchanger, a chiller package, and a gas-to-air heat exchanger. 11.The process of claim 9, wherein the at least one evaporative type coolercomprises a cooling tower.
 12. A system for cooling hot process gases,the system comprising: a multi-stage direct contact cooler comprising ahigh temperature stage and a low temperature stage; a first coolingdevice configured to cool a first cooling water circulated in the hightemperature stage, and a second cooling device configured to cool asecond cooling water circulated in the low temperature stage.
 13. Thesystem of claim 12, wherein each of the first and second cooling devicesis selected from the group consisting of an air-cooled heat exchangerand an evaporative type cooler.
 14. The system of claim 12, furthercomprising a third cooling device configured to cool the second coolingmedia upstream of the second cooling device.
 15. The system of claim 12,wherein a difference between a cooling water supply temperature of thefirst cooling water entering the high temperature stage and atemperature of partially cooled saturated process gases exiting the hightemperature stage is less than about 10° F.